Biology of the Soft Brown Scale, Coccus Hesperidum Linn., And
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BIOLOGY OF THE SOFT BROWN SCALE , COCCU S HE SP ERIDU.-i LINN ., AND CONTROL OF SOF'r d C \ L.E S ON HOLLY by WARREN CLIFFORD ADLERZ A THESIS submitted to OREGON STATE COLLEGE in partial fulfillment of the requirements for t h e degree of !A v T ER OF S CIENCE June 1955 APFROVEDI Redacted for Privacy Aggoolate Prtofereor of, Departnent of &rtorc1o6y fn 0hargo of ll3Jor .:- Redacted for Privacy Chelrma of Dopentuost of Strrtorologt Redacted for Privacy Chnlrren of 8ohool Oneduets Conmlttcr Redacted for Privacy Drcn of Orrduatc $ohool Drtc thasla le prorori1,oa F4 ^r, {1,, typoC by R:lta P. ldlcra ACKNO\iLEDGilENT The writer wiehe to ex~reBs sincere ap rec1ation to Dr . Knud G• . Swenson, Associate Professor, Oregon State College, under whose patient guidance this work was undertaken and completed. The writer would like to express hi appreciation to Dr . Paul o. Ritcher, Head of the Department of Entomology , for his guidance ~nd eneoura ~ ement . The writer is also indebted 't-O Dr . Charles H. Martin, ssooiate Professor. for helpful criticism of this thesis a nd Mr. E. A. Dickason , Asaistant Entomo og1st, Oregon Agricultural Experiment 5tation, for his gu1d nee in photography wnich resulted in illustl'ation of t,he thesis . To the staff and friends of the writer at Oregon vtate College , the writer expresses his gratitude. The writer is sincerely grateful to his wife , Rita P . Adlerz , for constant faith and encouragement. TABLE OF CONTENTS INTRODUCTION .................................. 1 E:CONOMI C I~PORTANCE • • • • • • • • • • • • • • • • • • • • • • • • • • • 2 DISTRIBUTION , HOSTS , 1\ND INJURY • • • • • • • • • • • • • • • 5 T. "ONOMIC GT TU S '\ D DESCRI'PTION • • • • • • • • • • • • • • 6 T~ONOMIC POSITION . ~ ..................... 6 SYNONYMY ............. .................... 8 Dl!:vCRIPTION .............................. 11 DE1;CRI ?TI ON OF bTAGES • • • • • • • • • • • • • • • • • • • • • • • • • 12 FI RST !NOT~ .•• .......................... 12 lJECOND INJTAR ~ ........................... 14 DULT • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 16 !..IFE HISTORY AND HABITS • • • • • • • • • • • • • • • • • • • • • • • 18 bEASONAL HISTORY • • • • • • • • • • • • • • • • • • • • • • • •• • 18 BI RTH OF CRAWLERS • • • • • • • • • • • • • • • • • • • • • • • • 21 FECUNDI TY • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 22 MOVEMENT OF CRAt'lLERS ~ND ADULTS • • • • • • • • • • 24 DI SPERSAL • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 24 }110LTI NG .~ ................................ 25 TEMPERATURE RELATI ONS • • • • • • • • • • • • • • • • • • • • 25 DI SCUSSION ............................... 26 OO~TROL ....................................... 27 GOFT BRO\'lN SCALE ...............- ~ ........ 27 N TURJ\L CONTROL ............. ........ 27 CH~MIC ~L CONTROL • • • • • • • • • • • • • • • • • • • • 29 Lt!:CANIU~~ • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 32 PULVIlARIA ............................... 34 ~JNG!C I D€ COMPATIBILI TY .................. 37 DI ..>CUJSION ............................... 38 SUMMARY ....................................... 40 BI BLI OG PHY • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •• • • 43 APPENDI X ...................................... 46 LIST OF TABLES Table 1 . ~1 ea surementn o crawlers in millimeters . 11t ·2 . Measurements of the firat 1natar settled s tage , in millimeter - • •••••••• 15 3 . Measurements of the second instar in mil 1m t or • ••••••••····~··••••••••• 17 4. "'1easur0mento of the adult i mmedia.·tely after the second ecdysis , in millimeters . ••••••••••••••••••••••••••• 18 5. Measurements of the fully matured adult, in millimeters . •• • •••••••••• · ••• 19 6 . Comparison of temperature data for experiment site and Corvallis for the period July 1 to November 30 . •••••• 25 1. Comparison of malathion and chlorth1on for control of Coccus hesper1dum on holly , Tigard, Oregon , 1954. • •• • •• •• •• • 33 8 . Comparison of three insecticides for control of Lecan1um nym hs on holly , Tigard, Oregon , 1954. • • • • • • • • • • • • • • • • • • 35 9. Comparison of malathion and chlorthion for control of Pulv1nar1a nymphs on camellia, Corvallis , Oregon, 1954. ••••• 37 LIST OF FIGURES F1s ure 1. Soft brown scale . A fully matured adult and two crawlers . t1v1ng specimens on holly. Eleven times natural size. • • •. • • • • • • • • • • • • • • • • • • • • .• • • 46 2 . Soft brown scal e . nettled first and second 1natar nymphs on holly . .......... 47 3 . Lecanium sp. Bodies of dead adults found covering eggs in the spring, on holly.. • • .. • • • • • • • • .• • • • • • • • • • • • .. • • • • • • 48 4 . Camellia scale . Immature stages. Early summer condition after eggs have hatched. Note number of individuals . •••••••• •••• 49 5. Camellia soale . Frothy egg masse s in June . Newly hatched nymphs oan also be seen her e . • • • • • • • • • • • • • • • • • • . • • • • .. • • • • • 50 BIOLOGY OF THE SOFT BR0 1ffl SCALE, COCCU t> HESPERI DUM LINN . ,1 AND CONTROL OF SOFT 13 CALE:J ON HOLLY INTRODUCTION The original descri t1on of the soft brown scale, Coccus hesner1dum L. • t.zas puol_is. hed in 1758 by Linnaeus 1n the tenth ed1t1on ·Of " Bystema Naturae 11 (12, p . 445) . This scale ts distributed. throughout the world and exhibits ·an amazing ada tab111ty in host select1on<t It i s a co.m mon pest of both citrus trees and ornamental plants. In Oregon the soft bro~m s ca le is a. common ·pest on ornamental plants , one of which i s holly .. Holly 1a an import nt plant in the s t a te of Oregon . · It is cultured extens ively 1n orchards where marketing of cut holly i s the objective and· it is utilized ~reely in landscaping. The scales ca.n be present in sufficient numbers to deface the leaves with their Ol'lrl bodies,. In addition the sooty mold which grows on their exudates can render the leaves orthlees f or \decoration or dis play . Both the home owner and the commercial grower are f a ced with these problems . \"fork on the other two scales included , 'tecaniurn sp. 1 . Sca les studied were identified by Dr. Harold Morrison, u ~s . o . A ., Agricultural Research uerv1oe, Beltsville . Md . 2 and :Pulv1n~r1a flocc1fera (West . ), comes a .s a natural outgrowth of the original problem. They are also in the group known as soft scales and are detrimental in a way similar to the soft brown scale. The three scales may occur on the same hosts and are difficult to dis tinSuish from one another except as adults or when reproducing. In the re roductive condition, eggs are found beneath Lecan1um scales . Eggs occur in a frothy mass behind Pulvinaria scales and living young are found beneath soft brown scales . As adults,. Coccu.s and Pulvinar!% scales re not easily separated. Lecan1um scales differ from both of these in being larger and distinctly dome- or bell- shaped. Much work has been done with the soft brown scale . However , it has not been the subject of extensive investigation to evaluate its characteristics in Oregon. This work has been undertaken to increase our information on the local habits of this scale, and to investigate the effect of some chemical controls . ECONOMIC IM ·ORTANCE The soft brown scale 1s one of' the most common 3 scales to be found in Oregon. lta host range includes many of the bro dleaf evergreen trees and shrub {19 , I p . 36) . This scale is a potential threat to cro s throughout its wide range, but it is generally con• sidered of secondary importance. Writers all over the world cite isolated instances where acute damage has occurred as a result of the activities of th1 scale, but most believe that generally the action of p ras1tes keeps it under control ~ In important fruit growing district 1n Peru, the soft brown scale occurs on mango but is not of economic importance due to the fact tha t it is controlled by natu ral enemies (30 , p . l20) . In Palestine this scale is cons idered the most important economic pest on citrus (16 , p . 325); however , when the population increases 1n May and June , natural enemies also increase and tend to control it. In valifornia, Quayle reported that the soft brown scale is usually restricted to isolated trees , and infestations generally disappear quickly due to the work of parasites (15 , p . l4) . These reports are typical of those found in the literature. In summary it appears that Coccua hesneridum L. is generally of secondary im port~ce due rimarily to natural enemies and becomes of major importance only when some factor upsets th1 natural s1tua.t1:on (31J¥!l •820), (10 , p . 711) and 4 (6' p . 593) . An example of the damage iihich ca n ooeur due to, soft bro\m scale aot1v1ty was indicated in a paper by Ewart and Elmer concerning their work in California (8• P•352) . Of the several unarmored or soft s cales which a ttack citrus trees in California, t hese authors lis ted four whleh t b.ey consid-ered of most 1mportano,e,: ::7·a1sset1a oleae (Burm . ), t he black s ca l e ; Cocoqs paeudoma.BJ10l1arum (Kuw .. ) , the c1tr1cola. scale; Icerfa J2Urches1' f.1ask . ; t he cottony cushion s oa.le; and Oo.cous heaperigum L. , t he soft brown seale. These authors have indicated t hat Coccus hes neridum was generally controlled by natural enemies .. Despite th1s f a.·ct, 1n:teetat1ons occasionally got out o·f hand and damage quickly resulted. and eo.onomie. ' Ewart. Elmer did their work where infes t a tions of these scales were severe enough that cop.trol measures were needed. As a result of their control of these